ELV (12 volt DC ) operated zone valves

[bernardgreen]

For the renovation of a Grade II listed thatched cottage I will need eight or nine zone control valves to control central heating flow to radiators and hot water tank coils. This is a DIY renovation of the building that will be my home.

The difficulty is these need to be operated by ELV motors ( 12 volt prefered ) and with position feed back micro switches.

A fully timed and zoned bespoke controller is being designed.

Before I design and build the valve actuators I have to ask if there is an easily available unit on the market. I have looked and spoken to the major manufacturers without sucess.

Motor direction by reversal of the DC supply. Stalling at end stops is not acceptable

Micro switches ( or similar ) to indicate fully open and fully closed

Micro switches ( or similar ) to remove power to motor if it over runs limits ( with diodes to allow motor to be backed out by reversal of supply )

Alternatively valve bodies where the spindle can be turned continuously would allow for the motor to always run in the same direction from open to closed and then in the same direction from closed to open.

Valve bodies need to be standard off the shelf items It is un-likely that three port valves with mid position will be needed.

 

[Gasman77]

Mysteryman -Do you think people may ' cackle' because you work for viessmann and is therefore highly likely you will tell posters to install your systems? Cackle, cackle

 

[Onetap]

A boiler such as a Viessmann Vitodens 200-W .........

Possibly no mains electricity, since he is looking for 12 V dc valves. Solar PV, wind turbine &/or wood burner, possibly?

Siemens SSC61, operates on 24 V DC, I'm sure you could figure out how to supply 24V DC. Belimo also do valves and actuators that operate on 24V DC. The actuators also have a 0-10 V DC proportional signal (10V = 100%, 0V = 0%). Probably relatively expensive, since they are intended for commercial modulating control rather than domestic on/off control, but then less costly than making actuators.

 

[bernardgreen]

The cottage does have mains electricity. The use of ELV ( 12 volt ) to operate zone valves is to enable the use of thinner cables and keep mains power well away from areas close to the thatched roof.

Before you commit yourself to what looks like a sophisticated well controlled system, take a look at the whole house.

I have looked at the whole house, and the system has been planned on that.

The layout of the rooms and 2 foot thick stone walls seriously compromise pipe runs and cable runs. It is more economical in the long term to have two hot water tanks, one at each end of the house, than to try and get short direct hot water pipes to both areas requiring hot water.

 

[Riddor]

12v in-line wax valve be any use?

http://www.heatmisershop.co.uk/In-Line-Wax-Valve-Heatmiser-VAL-012

edit..... think they are 240v... D'oh!!!

 

[Onetap]

The cottage does have mains electricity. The use of ELV ( 12 volt ) to operate zone valves is to enable the use of thinner cables and keep mains power well away from areas close to the thatched roof.

I'd use 24 V AC then, widely available for valve actuators. I believe there is a 24 V AC synchronous motor available that fits most domestic valves.

230 V conductors would be thinner for the same wattage, I believe.

You could even use pneumatics, best of luck in finding the components, though. Siebe was the last manufacturer I knew of, but my involvement was mostly in ripping it out. Still widespread in the USA, I believe, and where EMP resilience is required.

 

[Boilerman2]

Why not use Honeywell Smart TRV's??

 

[bernardgreen]

I'd use 24 V AC then, widely available for valve actuators. I believe there is a 24 V AC synchronous motor available that fits most domestic valves.

These hold the valve open by the motor being energised but stalled on the end stop. Lose power and the valve closes on the spring return

230 V conductors would be thinner for the same wattage, I believe.

The wire is thinner but the mains voltage requires thicker insulation making the over all diameter larger.

 

[Onetap]

These hold the valve open by the motor being energised but stalled on the end stop. Lose power and the valve closes on the spring return

Most domestic ones do, except Sunvic Momo valves, but there are reliability problems with those, allegedly. Google for Seered Sunvic. I don't know if the usual synchronous motor fits.

Commercial valves are usually 24 V AC. They are either 3-point (motor open, motor closed by reversing the power connection) or modulating with a 0-10V DC control signal. Spring return is available only as an optional extra.

The wire is thinner but the mains voltage requires thicker insulation making the over all diameter larger.

I thought that might be it; I did say 'conductors'.

 

[Norcon]

I will need eight or nine zone control valves to control central heating flow

Why do you want that many electrically controlled zones? TRV's do a decent job combined with a couple of zone valves.

If there's rooms unoccupied then turn down the trv's or turn them off.
And consider WC which has already been mentioned.

 

[bernardgreen]

TRV's do a decent job combined with a couple of zone valves.

Maybe they do in modern houses with "normal" height ceilings but this building has very high ceilings and experience of similar rooms with TRVs is that temperature control is not optimum.

If there's rooms unoccupied then turn down the trv's or turn them off.

One important requirement of the design spec is to avoid the need for this type of manual activity. The long term benefit of a zone valve per radiator against manually turning off a valve is worth the extra expense of the valve.

And consider WC which has already been mentioned.

A form of this is being included in the control system

 

[Onetap]

Maybe they do in modern houses with "normal" height ceilings but this building has very high ceilings and experience of similar rooms with TRVs is that temperature control is not optimum.

One important requirement of the design spec is to avoid the need for this type of manual activity. The long term benefit of a zone valve per radiator against manually turning off a valve is worth the extra expense of the valve.

A form of this is being included in the control system

2-port modulating valves with wall-mounted temperature sensors in each room. You're talking about a BMS installation; get a quote from a BMS outfit if you haven't already done so. It would be madness to start fabricating this from discrete components when it already exists.

 

[bernardgreen]

It does get close to BMS ( Building management system ) but not close enough to warrant that level of expense as a bought in system.

It probably would be madness to start from scratch if I was not an electronics designer. But I am and have already designed very similar modules for clients so designing the electronic modules to create a system that exactly suits the needs of this building is for me a simple task.

 

[Onetap]

It probably would be madness to start from scratch if I was not an electronics designer. But I am and have already designed very similar modules for clients so designing the electronic modules to create a system that exactly suits the needs of this building is for me a simple task.

There have been electronics designers and software designers working on the same problems since about 1980. If you think you can produce something comparable to a modern BMS system, I'd suspect you haven't used one.

If the cost still makes a home brew system the only option, that is a poor indication of the state of the UK controls market. The reason they have not filtered down to become available to UK domestic installers is IMHO due to the opoeration of a cartel.

 

[bernardgreen]

If the cost still makes a home brew system the only option, that is a poor indication of the state of the UK controls market.

Many items in central heating systems are over priced when one knows the cost to manufacture. Boiler control boards ( the PCB ) being one example that really annoys me. Over priced and in some cases assembled with very little effective quality control. I accept that design costs have to be recovered as well as various other head costs but amortising these over a few thousand boards should not turn a £ 45 (all components plus assembly) board into a £ 180 spare part. Cartel ? possibly but greed for profits and the idea of making repairs almost as expensive as new system to market more equipment

There have been electronics designers and software designers working on the same problems since about 1980.

True but they are working to a marketing requirement to sell as many ssytems as possible. This means most of the designs are aimed at meeting the needs of the most common type of house. It is un-economic to make them capable of meeting the needs of the unusual houses.